Item Has Already Been Added Error

3 posts, 0 answers
  1. Gohar
    Gohar avatar
    9 posts
    Member since:
    Dec 2015

    Posted 17 Dec 2015 Link to this post

    From filtering box, when I select Null and then select All then the following error occurs:

    Item has already been added. Key in dictionary: '(Blanks)'  Key being added: '(Blanks)'

    Please see the attached screenshot.

  2. Raphaël MANSUY
    Raphaël MANSUY avatar
    26 posts
    Member since:
    May 2005

    Posted 15 Mar in reply to Gohar Link to this post


    I have exactly the same issue.

    I've tried with the last version (2016 Q1) and I still have the problem.

    Is there a workaround available ?


    Thank you in advance

  3. UI for WinForms is Visual Studio 2017 Ready
  4. Dess
    Dess avatar
    1609 posts

    Posted 17 Mar Link to this post

    Hello Raphaël,

    Thank you for writing.

    I have logged it in our feedback portal. You can track its progress, subscribe for status changes and add your vote/comment to it on the following link - feedback item.

    I have also updated your Telerik points.

    Currently, the possible solution that I can suggest is to remove the unchecked node values from the dictionary: 

    this.radGridView1.FilterPopupInitialized += radGridView1_FilterPopupInitialized;
    RadListFilterDistinctValuesTable selectedValues;
    private void radGridView1_FilterPopupInitialized(object sender, Telerik.WinControls.UI.FilterPopupInitializedEventArgs e)
        RadListFilterPopup popup = e.FilterPopup as RadListFilterPopup;
        selectedValues = popup.MenuTreeElement.SelectedValues;
        popup.MenuTreeElement.TreeView.NodeCheckedChanged += TreeView_NodeCheckedChanged;
    private void TreeView_NodeCheckedChanged(object sender, TreeNodeCheckedEventArgs e)
        if (e.Node.CheckState == Telerik.WinControls.Enumerations.ToggleState.Off)
            if (selectedValues.Contains(e.Node.Text))

    I hope this information helps. Should you have further questions I would be glad to help.
    Do you need help with upgrading your AJAX, WPF or WinForms project? Check the Telerik API Analyzer and share your thoughts.
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